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Data Grid

Deferred Selection

Documentation

The DataGrid widget supports deferred row selection. When it is enabled, the DataGrid does not make requests for data until this is demanded from the API. In this demo, data is loaded when the jQuery Deferred object returned by the getSelectedRowsData() method is resolved. To specify initially selected rows, the selectionFilter option is used. Use deferred selection mode when working with a huge amount of remote data.

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import React from 'react'; import DataGrid, { Column, FilterRow, Selection } from 'devextreme-react/data-grid'; import Button from 'devextreme-react/button'; import query from 'devextreme/data/query'; import 'devextreme/data/odata/store'; var dataGrid; const MILLISECONDS_IN_DAY = 1000 * 60 * 60 * 24; const dataSource = { store: { type: 'odata', url: 'https://js.devexpress.com/Demos/DevAV/odata/Tasks', key: 'Task_ID' }, expand: 'ResponsibleEmployee', select: [ 'Task_ID', 'Task_Subject', 'Task_Start_Date', 'Task_Due_Date', 'Task_Status', 'ResponsibleEmployee/Employee_Full_Name' ] }; const selectionFilter = ['Task_Status', '=', 'Completed']; class App extends React.Component { constructor(props) { super(props); this.state = { taskCount: 0, peopleCount: 0, avgDuration: 0 }; this.onInitialized = this.onInitialized.bind(this); this.calculateStatistics = this.calculateStatistics.bind(this); } render() { return ( <div> <DataGrid id={'grid-container'} dataSource={dataSource} showBorders={true} defaultSelectionFilter={selectionFilter} onInitialized={this.onInitialized} > <Selection mode={'multiple'} deferred={true} /> <FilterRow visible={true} /> <Column caption={'Subject'} dataField={'Task_Subject'} /> <Column caption={'Start Date'} dataField={'Task_Start_Date'} width={'auto'} dataType={'date'} /> <Column caption={'Due Date'} dataField={'Task_Due_Date'} width={'auto'} dataType={'date'} /> <Column caption={'Assigned To'} dataField={'ResponsibleEmployee.Employee_Full_Name'} width={'auto'} allowSorting={false} /> <Column caption={'Status'} width={'auto'} dataField={'Task_Status'} /> </DataGrid> <div className={'selection-summary center'}> <Button id={'calculateButton'} text={'Get statistics on the selected tasks'} type={'default'} onClick={this.calculateStatistics} /> <div> <div className={'column'}> <span className={'text count'}>Task count:</span> &nbsp; <span className={'value'}>{this.state.taskCount}</span> </div> &nbsp; <div className={'column'}> <span className={'text people-count'}>People assingned:</span> &nbsp; <span className={'value'}>{this.state.peopleCount}</span> </div> &nbsp; <div className={'column'}> <span className={'text avg-duration'}>Average task duration (days):</span> &nbsp; <span className={'value'}>{this.state.avgDuration}</span> </div> </div> </div> </div> ); } onInitialized(e) { dataGrid = e.component; this.calculateStatistics(); } calculateStatistics() { dataGrid.getSelectedRowsData().then(rowData => { var commonDuration = 0; for (var i = 0; i < rowData.length; i++) { commonDuration += rowData[i].Task_Due_Date - rowData[i].Task_Start_Date; } commonDuration = commonDuration / MILLISECONDS_IN_DAY; this.setState({ taskCount: rowData.length, peopleCount: query(rowData) .groupBy('ResponsibleEmployee.Employee_Full_Name') .toArray() .length, avgDuration: Math.round(commonDuration / rowData.length) || 0 }); }); } } export default App;
import React from 'react'; import ReactDOM from 'react-dom'; import App from './App.js'; ReactDOM.render( <App />, document.getElementById('app') );
<!DOCTYPE html> <html> <head> <title>DevExtreme Demo</title> <meta http-equiv="X-UA-Compatible" content="IE=edge" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0" /> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/19.2.3/css/dx.common.css" /> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/19.2.3/css/dx.light.css" /> <link rel="stylesheet" type="text/css" href="styles.css" /> <script src="https://unpkg.com/core-js@2.4.1/client/shim.min.js"></script> <script src="https://unpkg.com/systemjs@0.21.3/dist/system.js"></script> <script type="text/javascript" src="config.js"></script> <script type="text/javascript"> System.import('./index.js'); </script> </head> <body class="dx-viewport"> <div class="demo-container"> <div id="app"></div> </div> </body> </html>
#grid-container { height: 400px; } .center { text-align: center; } .selection-summary { border: 1px solid rgba(161, 161,161, 0.2); padding: 25px; } .column { margin: 20px 30px 0 0; display: inline-block; white-space: nowrap; text-align: right; } .value { font-size: 40px; display: inline-block; vertical-align: middle; } .text { text-align: left; white-space: normal; display: inline-block; vertical-align: middle; } .avg-duration { width: 100px; } .count{ width: 40px; } .people-count { width: 65px; }
System.config({ transpiler: 'plugin-babel', paths: { 'npm:': 'https://unpkg.com/' }, defaultExtension: 'js', map: { 'react': 'npm:react@16/umd/react.development.js', 'react-dom': 'npm:react-dom@16/umd/react-dom.development.js', 'prop-types': 'npm:prop-types/prop-types.js', 'devextreme': 'npm:devextreme@19.2', 'devextreme-react': 'npm:devextreme-react@19.2', 'jszip': 'npm:jszip@3.1.3/dist/jszip.min.js', 'quill': 'npm:quill@1.3.7/dist/quill.js', 'devexpress-diagram': 'npm:devexpress-diagram', 'devexpress-gantt': 'npm:devexpress-gantt', // SystemJS plugins 'plugin-babel': 'npm:systemjs-plugin-babel@0/plugin-babel.js', 'systemjs-babel-build': 'npm:systemjs-plugin-babel@0/systemjs-babel-browser.js' }, packages: { 'devextreme': { defaultExtension: 'js' }, 'devextreme-react': { main: 'index.js' } }, babelOptions: { sourceMaps: false, stage0: true, react: true } });